1. Field of the Invention
The present invention concerns a system to be used on an automotive vehicle whereby the driver of said vehicle is provided with an improved view of the region rearward of the vehicle. The system comprises a closed circuit television system specially adapted for use on an automotive vehicle.
As is well known, automotive vehicles have one or more "blind spots" or areas where the driver or operator is unable to see an object behind the vehicle he is operating. This is particularly the case when the vehicle is comprised of a drive or tractor unit pivotably attached to a trailered cargo unit. In such instances, the driver, seated in the drive unit may not secure an adequate view of regions behind his vehicle by conventional rear-view mirrors.
The need for an adequate view of regions behind the vehicle is particularly necessary when the vehicle is in reverse motion as when backing toward a loading dock or into a parking space. In such situations, the view must be not only complete but in proper perspective, thereby permitting the driver to accurately manipulate the vehicle. The use of a television camera equipped with a wide angle lens and mounted at the rear of the vehicle may be contemplated to provide the necessary viewing function. Although wide angle lenses, having light acceptance angles of 30.degree. to 100.degree., provide a greater field of view than lenses of lesser acceptance angle, they may introduce distortion of perspective, particularly if the camera is positioned in a manner to produce a view different than the driver's normal view taken on a generally horizontal line of sight from a location close to median height of the vehicle.
Certain difficulties confront the installation of operational viewing equipment such as a television camera at the rear of a vehicle, particularly in the case of commercial vehicles such as trucks.
Weather factors such as rain, ice, high wind velocities and wide extremes of temperature and humidity impose severe limitations on the durability and continued functionality of ordinary equipment. Prolonged highway travel subjects the surfaces of a truck, particularly its rear surfaces, to accumulation of dirt and contact with chemicals utilized in the de-icing of roadways. Abrasive action is experienced by virtue of sand and other particulate materials propelled against the outer surfaces of the truck by adjacent vehicles in motion. The effects of vibration and jolting must also be taken into consideration. Additional protection of equipment is required with respect to vandalism, and damage due to impact.
Although certain aspects of equipment protection can be achieved by mounting viewing equipment within a truck adjacent its rear panel, such expedient might detract from cargo space and may additionally render the equipment vulnerable to impact damage from the cargo itself. This is especially the case with cargo compartments shaped as box-like rectangular structures having a flat rear panel. The structural framework of a truck may also provide a reasonably sheltered location for the mounting of a television camera, particularly that portion of the framework located below the cargo compartment at the rear end of the vehicle. Said portions of the structural framework generally contain panel sections and are frequently utilized for housing tail lights and turn indicator signals. However, an inside surface of the structural framework may not be able to accommodate bulky objects without interference with other components.
2. Description of the Prior Art
The use of a television camera to view the region behind a vehicle is disclosed in an article by J. F. Mason on pages 38 and 40 of Electronic Design 20, Sept. 28, 1972. It is stated at page 40 of said article that the image produced by the TV camera must be reversed to its mirror image in order to produce a view that drivers are accustomed to seeing. No specific manner of image reversal is disclosed.
A system for viewing rearwardly of a tractor-trailer vehicle by means of closed circuit television has been disclosed in U.S. Pat. No. 3,689,695 to Rosenfield. In said patent, a television camera is mounted atop a tractor or cab unit which pulls a trailered cargo compartment. Even though the camera is provided with a complex adjustable positioning system, its location atop the cab unit makes it impossible to view the region directly adjacent the rear of the trailered compartment.
Another system for viewing rearwardly of a tractor-trailer vehicle utilizing closed circuit television is disclosed in British Pat. No. 934,037 which utilizes a television camera mounted within a towed cargo trailer adjacent the top of the rear panel thereof. Although the camera is sheltered, its high position, chosen presumably to minimize interference with cargo, necessitates a downward camera angle to view the ground adjacent the rear of the trailer. Said downward angle produces views contrary to the driver's customarily perceived view.
French Pat. No. 2,302,648 discloses the use of a television camera for visual surveillance in buildings such as banks. In order to occupy minimal space behind a wall, the camera is mounted in sideways position to the rear of said wall. To facilitate scanning of a wide area, the camera is vertically oriented below a pivotably adjustable mirror located opposite a transparent window in side wall. Although an inverted image is produced by such arrangement, undisclosed means are presumably utilized to correct said image.
The use of a protective enclosure for a television camera has been disclosed in Australian Pat. No. 250,218.
It is an object of the present invention to provide a closed circuit television system for viewing rearwardly of an automotive vehicle. It is another object to provide a closed circuit television system for viewing rearwardly of an automotive vehicle, said system utilizing a television camera positioned so as to secure adequate view and perspective of regions rearwardly adjacent said vehicle. It is a further object of this invention to provide a closed circuit television system of the aforementioned nature wherein the television camera is mounted to an inside surface adjacent the rear of a cargo compartment and protected against the debilitating effects of weather and highway useage. It is a still further object to provide a closed circuit television system of the aforesaid nature utilizing a protected television camera mounted to an inside surface of a rear panel of a cargo compartment and which does not significantly intrude into said compartment.
These objects and other objects and advantages of the invention will be apparent from the following description.